I have a 91 lx 5.0 convert., It's a project car...but runs good ,and I've had no problems out of it until now, the last time I had the lights on was about 6 months ago, and just the other day i tried them, and all that would work is the parking lights, no headlights or high beams??? I checked the wires running to the turn sinal, the dimmer switch and to the headlight switch itself, I made sure that no wires had backed out, and I also sprayed some electronic corrosive cleaner on all contacts as well....any ideas???

 

Test the light sockets for 12v

 

yeah i would check for 12v like 1fastzook said but then i would also check ur connector to ur headlights. mine was cracked and sometimes the lights would come on and then shut off

 

You may want to check the bulbs themselves...